Vapor deposition apparatus

ABSTRACT

The vapor deposition apparatus includes a horizontally disposed, continuously rotating disc having a plurality of packets spaced about the periphery thereof, each containing a different evaporant source. Means directly heat only a portion of an annulus of said disc, including at least a portion of only one of said pockets. The disc has a thermal inertia such that sufficient heat is retained at all pockets, which have passed out of the immediate influence of said heat means, whereby to effect a simultaneous evaporation from all pockets.

United States Patent [151 3,695,217 Jacobsson Oct. 3, 1972 [54] VAPOR DEPOSITION APPARATUS 3,303,320 2/1967 Muller ..1l8/49.l X [72] Inventor; Jan Roland Jacobson, Taby 3,183,563 5/ 1965 Srnith, Jr ..l18/49.5 X Sweden 3,394,217 7/1968 Fisk ..2l9/121 EB 3,313,914 4 1967 R bert ,Jr. tal....2l9 275 X [73] Assignee AGA Akfienbolag LidingO, Swede" 2,753,280 7/1956 Mime? "118/48 UX [22] June FOREIGN PATENTS OR APPLICATIONS 1 45496 882,171 7/1953 Germany 1 18/49.]

[30] Foreign Application Priority Data Primary Examiner-Morris Kaplan June 13, 1969 Sweden ..8403/1969 Taylor and H 152 us. c1 ..118/49.5, 219/121 EB l57l ABSTRACT I ints 'rhe vapor deposition apparatus includes a horizon, of Search l 48, disposed continuously rotating disc having a plu 2l9/121 BB, 121 271; 117/932 rality of packets spaced about the periphery thereof, each containing a different evaporant source. Means directly heat only a portion of an annulus of said disc, [56] References C'ted including at least a portion of only one of said UNITED STATES PATENTS pockets. The disc has a thermal inertia such that sufficlent heat is retained at all pockets, whlch have passed 3,271,561 9/1966 Fledler et al ..2l9/27l out of the immediate influence f said heat means, 3,485,997 12/ 1969 Rhemherger ..1 17/933 X whereby to effect a simultaneous evaporation from all 2,482,329 9/ l 949 Dimmick ..1 18/49 pockets 2,745,773 5/1956 Weimer ..118/49 X 3,227,133 l/ 1966 Anderson et al. ..l 18/49.l 4 Claims, 3 Drawing Figures PATENTEDnm 3 m2 Fig.

v INVIN'I'OI JAN ROLAND JACOBSSON ATTORNEYS VAPOR DEPOSITION APPARATUS BACKGROUND OF THE INVENTION This invention relates to an apparatus for coating of surfaces of substrates with one or more substances by means of evaporation in a vacuum. The apparatus includes a vacuum chamber, a source for evaporation of the substances, means for heating these substances and holders for the substrates.

Previously known devices for this purpose usually have been constructed with an evaporation source of geometrical extension, which has been small compared to the substrates to be coated.

On heating these sources thermally or by electron beam heating it has been difficult to achieve a temperature distribution which has been uniform over the extension of the sources and reproducible from one evaporation to another. As a result the directional distribution of the vapor beam from the sources has been unsymmetrical and non-reproducible and this has caused a film thickness distribution on the coated substrates which has been non-uniform and nonreproducible. This invention has the objective of eliminating these drawbacks and facilitating production of surface coatings with uniform film thickness and in certain cases produce coatings consisting of mixtures of two or more, simultaneously or successively evaporated substances, the composition of which can be varied.

SUMMARY OF THE INVENTION The present invention concerns an apparatus for surface coating of a substrate by means of vacuum evaporation of one or several substances, including a vacuum chamber, a source for evaporating the substances in the form of disc which is rotatable around an axis through its center, and means which are arranged to heat at each moment a smaller part of the surface of the substances to be evaporated. The source for the substances to be evaporated has such a thermal inertia that a ring-shaped part of the source as a whole serves as evaporation source by being successively heated along its circumference and that the substrates to be coated are arranged above the ring-shaped source.

THE DRAWING FIG. 1 shows one possible form of the invention and FIGS. 2 and 3 show other forms of the sources for evaporating the substances in vacuum.

DESCRIPTION OF EMBODIMENTS The device shown in FIG. ll includes a vacuum chamber in the form of a bell jar l resting on a base plate 3 and a vacuum seal 2. The vacuum chamber is connected to a well known vacuum pump system 5 by means of a tube 4. Inside the chamber and held by a stand 6 is a holder 7 for a substrate 8, a surface of which substrate is to be coated. An electric motor 9 rests on base plate 3. A shaft of the motor carries the disc 10. The ring shaped circumferential groove ill in disc 10 serves as a crucible for the substances to be evaporated.

These substances can consist of a homogeneous mixture of different substances or grooves 11 can be divided into a number of sectors along the circumference, each of which contains one particular substance.

Heating of the substances can be achieved by means of electrons which are brought against the surface. As an example the elctron source can consist of a thermal cathode 12 held by a suitable holder.

The holder with the thermal cathode can be placed below disc 10. By means of electric and magnetic means 13 the electrons are accelerated, deflected and focused on part of groove 11 with the substances to be evaporated. In this way only a small part of the crucible is heated each moment, but since disc 10 with crucible 11 rotates relative to the heating element, all parts of the crucible 11 containing the substances to be evaporated will be successively'heated. This means that crucible 11 will be very uniformly heated and as a result the vapor distribution from the circumferential groove will also be uniform and reproducible. The film thickness on subject 8 will therefore be uniform. In the case that crucible 11 contains several different substances the proportions of these substances may be changed by making them occupy sectors of different lengths along the circumference.

Another possibility which permits variation of the proportions of several different simultaneously evaporated substances during the evaporation process is indicated in FIG. 2. FIG. 2 shows a disc 10 with specially shaped containers for the substances to be evaporated. In this particular form of the invention the groove ill has a larger radial extension which is bounded in this case by two concentric circles 14 and 15.

Further, the device for heating the substances is designed to concentrate heat at a part of the groove 11 at a certain distance from the center of the disc.

In FIG. 2 we assume that at a certain moment, heat is concentrated at a part of the groove 11' indicated as a dashed area 16. Further, the device is made with boundaries 17 between the different substances. The boundaries 17 may be constituted by for instance by watercooled metal walls or they may be obtained by shaping the different substances in a form indicated by sectors shown in FIG. 2. In FIG. 2 the boundaries are shown as parts of circles, but also other forms are possible. The boundaries are designed so that within ring shaped areas within groove 11' at different distances from the center of the disc different proportions of the different substances to be evaporated are obtained. Within the ring shaped areas 16 for instance the ratio between these substances is approximately equal whereas within the ringshaped areas at greater or smaller distances from the center, greater or smaller proportions of the one or the other substance will be evaporated. In the case of electron beam heating the deflection of the electron beam can be controlled by many well known methods and directed in such away that the diameter of the heated ring shaped area can be controlled. In this way the proportions of the evaporated substances can be varied during evaporation.

Another example of a design of this type of source is shown in FIG. 3. In this case disc 10 is provided with two concentric grooves 18 and 19, which are assumed to contain different substances. We assume that also in this example the device is provided with means to bring electron beams to hit the upper surface of disc 10 and that the electron beam can be directed to hit the one or the other grooves during certain controlled periods of time. Due to the thermal inertia of the substances a certain evaporation will take place along the ring shaped crucible also after heating has been terminated. By switching the beam position between crucibles 18 and 19 and permitting the beam to hit the crucibles at a certain time ratio a mixture of the substances in crucibles l8 and 19 can be produced. This ratio can be changed by varying the time during which the beam hits the two crucibles. Even if a complete mixture is not obtained due to the periodic heating of the substance, the switching frequency of the electron beam between the two grooves can be made high enough to produce mixtures which can be considered homogeneous for all normal optical purposes. Also in this case the proportions of the substances evaporated can be varied during evaporation by varying the ratio of the time for heating the one and the other crucible. The above examples have assumed heating to be achieved by a single heating device placed close to the circumference of disc 10. In certain cases it may be suitable to use several heating devices which are distributed along the circumference. Also other modifications are concievable within the frame work of the following patent claims. For instance the means for holding the rotatable disc may be designed to make the disc displaceable relative to the means for heating the substances as represented by arrow A in dotted lines in FIG. 1 whereby a directional control of the electron beam relative to the substances can be achieved.

Further, disc 10 instead of being provided with grooves containing the substances may itself consist of such substances for instance glass or quarts. Also other means for heating may be used such as laser beams or thermal radiation conveniently concentrated by means of a reflector.

I claim:

1. An apparatus for coating by vapor deposition comprising a vacuum chamber;

a continuously rotating, horizontally disposed, disc support for material to be evaporated;

said disc including a plurality of pockets about the periphery thereof whereby to support a plurality of different materials to be evaporated;

means to directly heat only a portion of an annulus of said disc and including at least a portion of only one of said pockets within said annulus;

said disc having a thermal inertia such that it maintains sufficient heat to simultaneously evaporate said plurality of different materials including the material in each of said pockets which are out of the immediate influence of said means to heat; and substrate support means disposed above and on a common axis with said disc whereby to effect said vapor deposition.

2. An apparatus according to claim 1, wherein the heat means comprises an electron beam source, and magnetic and electrostatic means for deflecting and directing the electrons towards the surface of the source substance to be evaporated.

3. An apparatus according to claim 2, wherein the means for deflecting the electrons are constructed to d' ct the el ctro beam towards arts of a ocket at different ra ial distances from t e axis of the disc whereby different proportions of evaporant composition are obtained.

4. An apparatus according to claim 1, including at least two of said means to heat said two means being placed at different positions along the circumference of the disc. 

1. An apparatus for coating by vapor deposition comprising a vacuum chamber; a continuously rotating, horizontally disposed, disc support for material to be evaporated; said disc including a plurality of pockets about the periphery thereof whereby to support a plurality of different materials to be evaporated; means to directly heat only a portion of an annulus of said disc and including at least a portion of only one of said pockets within said annulus; said disc having a thermal inertia such that it maintains sufficient heat to simultaneously evaporate said plurality of different materials including the material in each of said pockets which are out of the immediate influence of said means to heat; and substrate support means disposed above and on a common axis with said disc whereby to effect said vapor deposition.
 2. An apparatus according to claim 1, wherein the heat means comprises an electron beam source, and magnetic and electrostatic means for deflecting and directing the electrons towards the surface of the source substance to be evaporated.
 3. An apparatus according to claim 2, wherein the means for deflecting the electrons are constructed to direct the electron beam towards parts of a pocket at different radial distances from the axis of the disc whereby different proportions of evaporant composition are obtained.
 4. An apparatus according to claim 1, including at least two of said means to heat said two means being placed at different positions along the circumference of the disc. 